What is the use of hollystars? Purpose?
To give you the full answer:
Once you unlock skirmish 8 (The Ice map of your Turf) you will open the "Labyrinth" building.
In the Labyrinth you need to use Holy Stars to be able to hit the Dragon. At every hit, the dragon gives you drops: rss, gold, speedups, energy and so on.
You have yo hit the dragon 10 times to kill it, once it's killed there is a chance for the Goblin to pop up. The Goblin gives Gems when you hit it.
Also - if you manage to kill the goblin, you can win the jackpot from the right bottom side of the screen when you are in the Labyrinth